Twelve people were arrested this week for the various parts they played in a massive cocaine smuggling operation at the Luis Muñoz Marín International Airport in Puerto Rico.

Authorities say the defendants – who are airport employees, as well as current and former agents with the Transportation Security Administration – were responsible for smuggling approximately 20 tons of cocaine through the airport from 1998 to 2016.

The defendants were said to have worked in unison to get cocaine-laden suitcases through airport security without detection, while those transporting the drugs were given the “all clear” by security personnel involved in the operation to board designated planes.

The investigation was launched by the TSA as part of an ongoing effort aimed at uncovering misconduct and security threats by employees.